Choosing the correct size and type of input capacitor helps minimize the voltage ripple caused by the switching of the LM3645 boost converter and reduce noise on the boost converter's input pin that can feed through and disrupt internal analog signals. In the typical application circuit a 10-µF ceramic input capacitor works well. It is important to place the input capacitor as close as possible to the LM3645 input (IN) pin. This reduces the series resistance and inductance that can inject noise into the device due to the input switching currents.